1. Field of Disclosure
The present disclosure relates to instruments used in orthopedic surgery, and, in particular, to a femoral component instrument, which can be used as an inserter, impactor and extractor for use in the placement, impaction and extraction of a femoral prosthesis or femoral provisional component, for example.
2. Description of Related Art
The knee is the joint between the femur and the tibia. The knee joint is formed of a pair of condyles located at a distal portion of the femur, a tibial plateau located at a proximal end of the tibia and shaped to mate with the pair of condyles, and a pair of menisci positioned between the tibial plateau and the condyles. A knee may incur wear, significant disease, or trauma that warrants replacement of the knee with a prosthetic knee implant including prosthetic components such as a femoral component to replace the distal end of the femur, a tibial component to replace the proximal end of the tibia, and a bearing insert to replace articulating tissue between the femur and the tibia. The condyles of the prosthetic femoral component will have a shape corresponding to the shape of the natural condyles of the distal femur.
Orthopedic procedures for the replacement of all, or a portion of, a patient's joint typically require reshaping of the bones of the knee joint to receive such prosthetic components. Procedures for implanting a total knee prosthesis involve preparing and reshaping both the distal end of the femur and the proximal end of the tibia prior to implanting the respective prosthetic components. Resection of the femur generally involves making five intersecting generally planar cuts, and resection of the tibial plateau generally involves a single cut. The amount of bone removed is determined, in part, by the size and type of components being implanted.
During a surgical procedure to implant a prosthetic knee joint, a provisional femoral component and a provisional tibial component can be placed on a distal femur and proximal tibia, respectively, after resecting the distal femur and proximal tibia. The provisional components assist with confirming the proper size and position of the permanent femoral and tibial components. The provisional components typically come in a range of sizes representative of the size and shape of the permanent components of the chosen prosthesis system. Provisional components are typically selected after making a preliminary determination of the proper size of the permanent components. A trial reduction of the knee joint with the provisional components in place may indicate that the preliminary size determination was not ideal. Alternative provisional components can then be selected and another trial reduction performed. After determining the proper size components, final prosthesis components are seated. Proper insertion and extraction of the provisional components and subsequent placement of the final prosthesis components requires reliable grasping and manipulation of the provisional and final prosthesis components. Because the inserter of the present disclosure is usable with both provisional and final prosthesis components, “femoral components” will be generically used in this document to denote either a provisional or a final prosthesis component.
An inserter can be utilized to grasp and hold the various femoral components to facilitate placement or removal of the same during the surgical procedure. Femoral component inserters can utilize a pad to contact the condyles of the femoral component in conjunction with an opposing element placed against the bone contacting surface of the femoral component and drawn toward the pad to thereby assert a compressive force against opposing sides of the femoral component to hold the femoral component to the inserter. One such inserter is described in the Zimmer® MIS Intramedullary Instrumentation Surgical Technique for NexGen® Cruciate Retaining and NexGen® Legacy Posterior Stabilized Knees submitted herewith in an Information Disclosure Statement (see, e.g., pages 36 and 37), the entire disclosure of which is hereby explicitly incorporated by reference herein, and in U.S. Patent App. Publ. No. 2006/0200162, entitled “Total Knee Arthroplasty Instruments,” the entirety of which is hereby incorporated by reference herein.
A typical knee prosthesis system includes not only a variety of different sized femoral components but also a variety of femoral component types, offering differing levels of constraint. For example, a knee prosthesis system may include a number of sizes of a highly unconstrained knee prosthesis for use in cases where the natural ligaments can be retained to provide stability to the joint. Such prostheses are typically referred to as cruciate retaining (“CR”) prostheses. The chosen prosthesis system may also include a number of sizes of a more highly constrained knee prosthesis including one which utilizes a femoral cam and a tibial spine to stabilize and/or guide movement of the prosthetic components relative to each other. Such prostheses are typically referred to as posterior stabilized (“PS”) prostheses. CR and PS femoral components typically incorporate different features on their bone contacting sides. For example, PS femoral components can include a box extending proximally from the distal bone contacting surface to accommodate the spine of the corresponding tibial component.
To accommodate alternative insertion of, for example, PS and CR femoral components, alternative inserters, i.e., one particular to the CR implant and one particular to the PS implant may be utilized. During certain surgical procedures, a surgeon may, intraoperatively, decide that a more constrained prosthesis is needed. For example, a surgeon may preoperatively decide that a CR prosthesis is indicated, but during surgery determine that joint physiology requires a more constrained prosthesis such as a PS prosthesis. In such circumstances, a surgeon may alter his choice of both implant and inserter.
After inserting the PS or CR prosthesis onto a prepared distal femur of a patient, a surgeon utilizes an impactor device separate from the inserter to impact the inserted prosthesis against the contacting bone. As securement mechanisms of inserters tend to secure to a bone contacting surface of a prosthesis, utilizing the inserter as an impactor is generally not possible. Owing to the extension of the securement mechanism beyond the prosthesis contacting surface of the inserter, the securement mechanism could interrupt the desired contact between the bone contacting surface of the prosthesis and the bone to be contacted and/or impact portions of the distal femur aligned with the intercondylar notch of the femoral component.